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Title: Diversity strategies for MIMO communication systems
Author: Zhang, Fan
ISNI:       0000 0004 2676 4906
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2010
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This thesis proposes a joint spatial diversity scheme in MIMO systems in order to improve the transmission reliability of the wireless links, thereby to extend the transmission range and increase the information throughput. Cyclic delay diversity (CDD) and antenna selection are employed here for their low complexity, high flexibility, no spectrum efficiency reduction and high compatibility with many existing standards. A bit error performance bound for CDD system with orthogonal frequency division multiplexing and convolutional coding in multipath Rayleigh fading channel is generated, which renders a fundamental understanding of the mechanism of CDD and can be used instructively for CDD system design. A transmit cyclic delay diversity and receive antenna selection (TCDD/RAS) system is proposed here to achieve a performance gain with lower additional complexity and no data rate reduction compared with a transmit orthogonal space-time block coding (OSTBC) system, which is combined with the optimum receive antenna selection scheme. A hybrid system with both OSTBC and CDD in the transmitter and antenna selection in the receiver is also derived to avoid the high complexity requirement and data rate degradation of the OSTBC system as well as the performance loss of the CDD system. A receive antenna selection criterion for the TCDD/RAS system based on the previous performance analysis results is defined, however it demands high computational complexity. Therefore a much simpler and faster selection rule, named maximum minimum post-processing SNR criterion, is generated for the TCDD/RAS system in flat fading channels and another maximum group minimum post-processing SNR selection principle is developed in frequency selective channels. Both of these two selection rules achieve higher diversity gains with lower additional complexity compared with the traditional norm and capacity selection rules. Two relay systems embedded with the TCDD/RAS scheme are also constructed: the MIMO relay system and the cooperative relay system. The joint diversity scheme in the MIMO relay system obtains a higher diversity gain than in the cooperative relay system. Moreover, these two relay systems could be combined to a system with multiple cooperative relay nodes on which multiple antennas are deployed depending on the practical requirement in the future wireless communication systems.
Supervisor: Edwards, David Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Communications engineering (optical,microwave and radio)